This invention relates to photonic devices in general, and more particularly to tunable filters and tunable lasers.
Tunable Fabry-Perot filters and tunable vertical cavity surface emitting lasers (VCSEL""s) have recently generated considerable interest in the art. This is because these devices are believed to have application for a wide range of different optical components and systems, e.g., wavelength division multiplexing (WDM) fiberoptic systems, switches, routers, highly compact spectroscopic interferometers, optical trans-receivers, etc.
In some tunable Fabry-Perot filters and in some tunable VCSEL""s, tuning is achieved by using an electrostatic field to move a top mirror relative to a bottom mirror, whereby to change the length of the Fabry-Perot cavity and hence tune the wavelength of the device.
While such a construction is advantageous in that it provides a fast and easy way to tune the device, in practice it has proven difficult to produce relatively uniform devices. Significant performance variations typically occur from device-to-device and from batch-to-batch.
Accordingly, one object of the present invention is to provide an improved tunable Fabry-Perot filter.
Another object of the present invention is to provide an improved method for fabricating a tunable Fabry-Perot filter.
And another object of the present invention is to provide an improved tunable VCSEL.
Still another object of the present invention is to provide an improved method for fabricating a tunable VCSEL.
These and other objects are addressed by the present invention.
In one form of the invention, there is provided a tunable Fabry-Perot filter which comprises a substrate, a bottom mirror mounted to the top of the substrate, a bottom electrode mounted to the top of the bottom mirror, a thin membrane support atop the bottom electrode, a top electrode fixed to the underside of the thin membrane support, a reinforcer fixed to the outside perimeter of the thin membrane support, and a confocal top mirror set atop the thin membrane support, with an air cavity being formed between the bottom mirror and the top mirror, and with the thin membrane support being in the form of a dome with openings therein, with the openings being small enough, and with sufficient distance therebetween, so as to substantially not affect the overall structural integrity of the dome, while still allowing chemical access to the region inside the dome.
In another form of the invention, there is provided a tunable VCSEL which comprises a substrate, a bottom mirror mounted to the top of the substrate, a gain region mounted to the top of the bottom mirror, a bottom electrode mounted to the top of the gain region, a thin membrane support atop the bottom electrode, a top electrode fixed to the underside of the thin membrane support, a reinforcer fixed to the outside perimeter of the thin membrane support, and a confocal top mirror set atop the thin membrane support, with an air cavity being formed between the bottom mirror and the top mirror, and with the thin membrane support being in the form of a dome with openings therein, with the openings being small enough, and with sufficient distance therebetween, so as to substantially not affect the overall structural integrity of the dome, while still allowing chemical access to the region inside the dome.